Under the Federal Rules of Civil Procedure, people that sue you or your department may obtain discovery regarding any non-privileged matter relevant to their claims or your defense, including requesting that you or the department "produce... any (relevant) designated documents or electronically stored information." Fed. R. Civ. P. 26(b); 34(a).
We may be familiar with court decisions regarding "expectation of privacy" in the criminal context where the application of the Fourth Amendment is unquestioned. It's a very different ball game in civil litigation. A civil litigant's expectation and intent that communications be private is not a basis for shielding relevant communications from discovery. EEOC v. Simply Storage Mgmt., LLC (link below).
In Mackelprang v. Fidelity Nat'l Title Agency of Nevada Inc., 2007 WL 119149 (D. Nev. 2007), the defendants checked out the plaintiff's public MySpace page after she sued them for sexual harassment. More important, the court held the defendants could discover private messages exchanged with third parties that contained information regarding her alleged sexual harassment and emotional distress.
In the personal injury case of Romano v. Steelcase Inc. (link below), the plaintiff's public social network pages revealed an active lifestyle inconsistent with her injury claims. The court then ruled she had to produce historical and deleted pages and related information and that she could not hide "behind self-regulated privacy settings."
There are huge implications in the above rulings for officers and departments involved in civil lawsuits. Postings involving locker-room bravado or even just cop humor ("Officer, what did you feel when you shot that man?" "Recoil.") may well find their way into court. As I disclaimed, I've never been a civil attorney but I'd love to have the previous statement for not just the liability phase but also when it comes to determining whether punitive damages are appropriate.
Google "e-discovery." An entire cottage industry of "e-discovery" businesses and law firms has sprung up. People are making a living combing the internet for electronically stored information that might be used to impeach you in court.
Light a fire under the prosecutor
Consider suggesting that the prosecutor file a pre-trial motion regarding any use the defense intends to make of online information to impeach witnesses. The support for such a motion is all the false positives and fraud that can occur. I've provided a couple of links below you can give your very busy prosecutor regarding social media hacking she can use in the motion.
The prosecutor should argue that early discovery of such information is necessary to check it for false positives and fraud, which are common, so that the trial will not have to be interrupted and delayed to complete such investigation.
Jurors have internet access, too
This is a whole separate topic but jurors spend lots of down-time in Wi-Fi court buildings. This is causing lots of problems. A Reuters Legal analysis found that jurors' forays on the Internet have resulted in dozens of mistrials, appeals and overturned verdicts in the last two years. (Link below.)
Courts are scrambling for jury instructions to address the issue. (Link below.) Testifying officers need to consider that not all juror web surfing may be prevented or discovered.
So, the question is - are you comfortable with a juror who will be deciding your credibility seeing and hearing everything you've posted online? In fact, that's a good question to ask before every posting.
Let's call this the Officer's Facebook Juror Credibility Test and you need to take the test because you are a law enforcement officer and for no other reason. Sound unfair? Then you need to get another job. Fact is, your credibility is judged by a different and higher standard than any other witness a prosecutor calls to the stand because of what you and your badge represent.
What you don't know can hurt you
Much of what gets posted becomes a permanent record somewhere. Facebook, for one, retains all your information even if you close your account. It's just waiting there for a subpoena.
Did you know that photos can contain embedded information like GPS coordinates showing where the photo was taken and when, even the camera's serial number? (Link below to A growing trend: Social media as legal evidence.)